It's been two months since I got my new Grand Touring Le 900 ace 2016. Great sled by the way. In the beginning, I was disappointed about the fuel mileage, since it shows average 14-16 liters pr. 100 km in the ECO mode at cruise speed (30-50 km pr. hour). I used it a lot, and not with the top speed, since it was new, and need to get a first time service. The service was done, and I could feel that the engine has changed. The performance has increased, especially in the ECO mode. Then I could see that it averaged 9-11 liters pr. 100 km. The better fuel mileage was noticeable. But then something changed again. I was traveling, then I reached a lake, so I drove at top speed around 5 minutes. But somehow the engine decreased its perfomance. I couldn't increase the speed. The engine was somehow confused, since it wouldn't go above 80 kilometers pr. house. I stopped a minute and tried again. Now it could go up to around 110 kilometers pr hour at sport mode. Slower than before. It was weird. And the fuel mileage changed too, as before it was serviced. I called the dealer, and they said that they might be water in the fuel tank. They advised me to buy Redex fuel additive, so it could remove the water. Done, I put some. Still no change. We adjusted the drive belt too. Still no change. Does anyone knows what the problem might be?